Hi JK,
I'd suggest you click this link to the Android Tablet Q&A section. Read the "Sticky:" threads at the beginning for some good general information about tablets and Android. There's also an Android dictionary in there that explains a lot of the terms used around the forum. Have fun and enjoy the forum!
Spider
Hi, a custom rom is a version of the softwate that runs your Tablets that has been made by someone other than the manufacturer of the device. They are generlly optomised for better performance than the original or stock rom( or firmware as its known). In most cases these roms root your Tablets. This makes the Tablets more accessible & easier to play around with. In many cases chinese Tablets firmware is not great. & replacing it with a custom rom is the best way to get apps like google play etc. Which aren't licensed to chinese devices. There are some risks but generally most of them work better and improve the running of your Tablets. Each device has its own cpu types & you will see frm various forum pages many different custom roms suited to each cpu. Hope this answers some of your questions.